In recent years there has been an increased interest in catalysts for propane leak detection. Since propane is heavier than air and tends to collect in pockets, along floors, and the like, it is necessary to promptly sense the presence of the leaking propane, to foreclose the chance of a gas build up resulting in an explosion. Catalytic detectors have been known for the detection of propanes and other hydrocarbons. The catalysts must be maintained at an elevated standby temperature (such as 300.degree. C.) in order to be efficient in operation. This has been accomplished in the past by the use of electric heating coils around the catalyst. When propane is in the presence of the catalyst a reaction occurs which causes the catalyst to be heated to a temperature higher than the standby temperature. This change in temperature can be recognized as indicating the presence of the gas.
In the present invention there is disclosed the use of a heat pipe for conveying waste heat from a standing pilot flame to the catalyst so that no electrical or other energy source need be expended in maintaining the standby temperature of the catalyst. A heat pipe is generally defined as a heat transfer device consisting of a sealed metal tube with an inner lining of wicklike capillary material and a small amount of fluid in a partial vacuum; heat is absorbed at one end by vaporization of the fluid and is released at the other end by condensation of the vapor.